import java.util.Scanner;
public class text11 {
    public static int fibo(int n) {
        if (n == 1) {
            return 0;
        } else if (n == 2) {
            return 1;
        } else return fibo(n - 1) + fibo(n - 2);
    }

    public static void main1(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int a = fibo(n);
        System.out.println(a);
    }

    public static void main3(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        ht(n, 'a', 'b', 'c');
        sc.close();
    }

    public static void ht(int n, char a, char b, char c) {
        if (n == 1) {
            System.out.println(a + "->" + c);
        } else {
            ht(n - 1, a, c, b);
            System.out.println(a + "->" + c);
            ht(n - 1, b, a, c);
        }
    }


}